Bajkowski A S, Friedmann H C
J Biol Chem. 1982 Mar 10;257(5):2207-11.
L-Alanine:4,5-dioxovalerate aminotransferase, the enzyme that catalyzes the transamination between alanine and 4,5-dioxovalerate to yield delta-aminolevulinate and pyruvate, has been purified from extracts Clostridium tetanomorphum by acetone precipitation and successive tetanomorphum by acetone precipitation and successive chromatography on Sephadex G-150, hydroxyapatite, Octyl-Sepharose, and SP-Sephadex C-50. The enzyme is pure by the criterion of disc gel electrophoresis with varying polyacrylamide concentrations. It is dimeric, and has an apparent molecular weight of 111,000. Each molecule contains 2 molecules of pyridoxal 5-phosphate. The apparent Km values for 4,5-dioxovalerate and L-alanine are 0.26 and 1.96 mM, respectively. In addition to alanine, glutamate also is an effective amino group donor. The enzyme is inhibited by various keto acids as well as by inhibitors of pyridoxal phosphate-containing enzymes. It was possible to show that 4,5-dioxovalerate is formed by cultures of C. tetanomorphum when grown in the presence of 0.2 M levulinate, an inhibitor of 5-aminolevulinate dehydratase.
L-丙氨酸：4,5-二氧戊酸转氨酶，即催化丙氨酸与4,5-二氧戊酸之间的转氨作用以生成δ-氨基乙酰丙酸和丙酮酸的酶，已通过丙酮沉淀法及后续在葡聚糖凝胶G-150、羟基磷灰石、辛基琼脂糖和SP-琼脂糖凝胶C-50上的层析，从破伤风梭状芽孢杆菌提取物中纯化出来。根据在不同聚丙烯酰胺浓度下的圆盘凝胶电泳标准，该酶是纯的。它是二聚体，表观分子量为111,000。每个分子含有2个磷酸吡哆醛分子。4,5-二氧戊酸和L-丙氨酸的表观Km值分别为0.26和1.96 mM。除了丙氨酸外，谷氨酸也是一种有效的氨基供体。该酶受到各种酮酸以及含磷酸吡哆醛酶的抑制剂的抑制。有可能表明，当破伤风梭状芽孢杆菌在0.2 M乙酰丙酸（一种5-氨基乙酰丙酸脱水酶的抑制剂）存在下生长时，其培养物会形成4,5-二氧戊酸。
